With the advent of wireless networks and increased demand for multimedia-data transmission, there is an increasing need for studies on effective transmission. Furthermore, the need to transmit high-quality video, such as digital versatile disk (DVD) images and high definition television (HDTV) images, between various home devices in a wireless manner is increasing.
Currently, technology standardization for transmitting large amounts of data in a wireless home network is in progress by a task group of IEEE 802.15.3c. This standard, called “mmWave” (Millimeter Wave), uses electromagnetic waves having millimeter wavelengths (that is, in the range of 30 to 300 GHz) for transmission of data. This frequency band is an unlicensed band used for telecommunication, radio astronomy, and vehicle-collision prevention.
The carrier frequency of IEEE 802.11b and IEEE 802.11g is 2.4 GHz, and the channel bandwidth is approximately 20 MHz. Further, the carrier frequency of IEEE 802.11a and IEEE 802.11n is 5 GHz, and the channel bandwidth is approximately 20 MHz. In contrast, mmWave uses a carrier frequency of 60 GHz, and has a channel bandwidth of around 0.5 to 2.5 GHz. Hence, mmWave has much higher frequencies and channel bandwidths than the conventional IEEE 802.11 line standards. Likewise, by using high-frequency signals having millimeter wavelengths, a very high transmission rate of several Gbps units can be realized, and the size of an antenna can be made less than 1.5 mm, thereby implementing a single chip that includes an antenna.